Solve for $x$ and $y$ using substitution. ${2x-y = 5}$ ${x = -y+1}$
Solution: Since $x$ has already been solved for, substitute $-y+1$ for $x$ in the first equation. ${2}{(-y+1)}{- y = 5}$ Simplify and solve for $y$ $-2y+2 - y = 5$ $-3y+2 = 5$ $-3y+2{-2} = 5{-2}$ $-3y = 3$ $\dfrac{-3y}{{-3}} = \dfrac{3}{{-3}}$ ${y = -1}$ Now that you know ${y = -1}$ , plug it back into $\thinspace {x = -y+1}\thinspace$ to find $x$ ${x = -}{(-1)}{ + 1}$ $x = 1 + 1$ ${x = 2}$ You can also plug ${y = -1}$ into $\thinspace {2x-y = 5}\thinspace$ and get the same answer for $x$ : ${2x - }{(-1)}{= 5}$ ${x = 2}$